In vitro development of cyathostomin larvae from the third stage larvae to the fourth stage: morphologic characterization, effects of refrigeration, and species-specific patterns     

Emanuele Brianti  Salvatore Giannetto  Donato Traversa  Sharon R. Chirgwin  Krishna Shakya  Thomas R. Klei   《Veterinary parasitology》2009,163(4):348-356

A mixed population of equine cyathostomin (Nematoda, Strongyloidea) infective third stage larvae (L3) was cultured in vitro using a cell-free medium. Some L3 were cultured immediately after Baermann collection from fecal cultures, while others were kept in water at 4 °C for 7 days before initiating the in vitro cultures. Cultures were examined daily for viability. At days 2, 7, 14 and 21 larvae were collected for identification of developmental stage and morphological changes, using both light and scanning electron microscopy. Larvae were classified as early L3 (EL3), developing L3 (DL3), late L3 (LL3) and fourth stage larvae (L4) on the basis of morphological features. Viability remained high throughout the entire study period in cultures of both non-refrigerated (84.7%) and refrigerated (77.4%) larvae. However, viability of the non-refrigerated was significantly greater from 7 through 21 days of culture. Significant differences were also observed in the percentage of DL3 between the non-refrigerated and refrigerated larval cultures by day 7. The highest percentage of DL3 larvae (22.5%) was reached at the end of study in those larvae that were not previously refrigerated. The data suggests that prior refrigeration decreases viability and slows L3 development. At day 21 LL3 larvae were only a small percentage of the DL3: 6.9 and 5% in non-refrigerated and refrigerated cultures, respectively. Few of these larvae freed themselves from the L3 cuticle and moulted to L4 stage. Characteristics of individual species in vitro developmental patterns were determined by the molecular identification of individual larvae in pools of larvae randomly collected at days 0 and 21. Seven species (Coronocyclus coronatus, Cylicostephanus goldi, Cylicostephanus longibursatus, Cyathostomum catinatum, Cylicocyclus nassatus, Cylicocyclus ashworthi, Petrovinema poculatum) were identified in the day 0 pool. The greatest tendency to develop in vitro was shown by the genus Cylicostephanus with the species C. goldi and C. longibursatus that developed to the LL3-L4 stages. C. nassatus, C. ashworthi and C. coronatus did not progress in their development beyond the EL3 stage, while no apparent signs of development were registered for C. catinatum.  相似文献   

Effect of bupivacaine on epidural analgesia produced by xylazine or medetomidine in buffaloes (Bubalus bubalis)     

Virendra Singh MVSc     Amarpal MVSc  PhD    Prakash Kinjavdekar MVSc  PhD  & Hari P Aithal MVSc  PhD 《Veterinary anaesthesia and analgesia》2009,36(1):77-85

ObjectiveTo evaluate and compare the effect of epidural bupivacaine on analgesia produced by epidural xylazine or medetomidine in buffaloes.Study designProspective, blinded study.AnimalsTen male buffalo calves (6-8 months of age; body weight 70-90 kg) were used on two occasions to conduct a total of 20 investigations.MethodsCaudal extradural analgesia was produced in four buffalo calves each by the injection of either xylazine (0.05 mg kg^?1), medetomidine (15 μg kg^?1) or 0.5% bupivacaine (0.125 mg kg^?1), or combinations of xylazine and bupivacaine (0.05 and 0.125 mg kg^?1), or medetomidine and bupivacaine (15 μg kg^?1 and 0.125 mg kg^?1) at the first intercoccygeal extradural space. Analgesia was tested using deep pinprick stimuli.ResultsExtradural administration of xylazine or medetomidine resulted in complete analgesia of the tail, perineum, inguinal region and the upper parts of the hind limbs, which was faster in onset and longer in duration in the medetomidine group than in the xylazine group. Addition of bupivacaine increased the intensity of the analgesia produced by xylazine, but not that produced by medetomidine. All the drugs caused mild to moderate ataxia, but signs of sedation were apparent only in animals which received xylazine or medetomidine. The extradural injections of all the drugs caused significant decrease in heart rate (p = 0.024), respiratory rate (p = 0.026) and rectal temperature (p = 0.036) from the respective baseline values, but the differences between the groups were not significant.ConclusionsMedetomidine produced a longer duration of analgesia than that produced by xylazine. Bupivacaine prolonged the analgesia produced by xylazine, but the analgesia produced by the combination of medetomidine and bupivacaine was not superior to that produced by medetomidine alone.Clinical relevanceBupivacaine may be used to prolong the extradural analgesia produced by xylazine, but not that produced by medetomidine in buffaloes.  相似文献   

Rapid development of enhanced atrazine degradation in a Dundee silt loam soil under continuous corn and in rotation with cotton     

Zablotowicz RM  Krutz LJ  Reddy KN  Weaver MA  Koger CH  Locke MA 《Journal of agricultural and food chemistry》2007,55(3):852-859

Mississippi Delta cotton (Gossypium hirsutum L.) production in rotation with corn (Zea mays L.) was evaluated in field experiments from 2000 to 2005 at Stoneville, Mississippi. Plots maintained under minimum tillage were established in 2000 on a Dundee silt loam with treatments including continuous cotton or corn and alternate cotton-corn rotations. Mineralization and dissipation of 14C [ring]-labeled atrazine were evaluated in the laboratory on soils collected prior to herbicide application in the first, second, third, and sixth years of the study. In soils collected in 2000, a maximum of 10% of the atrazine was mineralized after 30 days. After 1 year of herbicide application, atrazine-treated soils mineralized 52-57% of the radiolabeled atrazine in 30 days. By the sixth year of the study, greater than 59% of the atrazine was mineralized after 7 days in soils treated with atrazine, while soils from plots with no atrazine treatment mineralized less than 36%. The data also indicated rapid development of enhanced atrazine degradation in soils following 1 year of corn production with atrazine use. Atrazine mineralization was as rapid in soils under a rotation receiving biannual atrazine applications as in soils under continuous corn receiving annual applications of atrazine. Cumulative mineralization kinetics parameters derived from the Gompertz model (k and ti) were highly correlated with a history of atrazine application and total soil carbon content. Changes in the soil microbial community assessed by total fatty acid methyl ester (FAME) analysis indicated significant interactions of cropping system and sampling date, with FAME indicators for soil bacteria responsible for differences in community structure. Autoclaved soil lost all ability to mineralize atrazine, and atrazine-mineralizing bacteria were isolated from these plots, confirming the biological basis for atrazine mineralization. These results indicate that changes in degradative potential of a soil can occur rapidly and some changes in soil properties may be associated with cropping systems, which can contribute to enhanced atrazine degradation potential.  相似文献   

RADIOGRAPHIC DIAGNOSIS: MEDIASTINAL PARATHYROID CYST IN A CAT     

Scot W.  Swainson  DVM  O. Lynne  Nelson  DVM  MS  Yosiya  Niyo  DVM  PhD  Krishna G.  Miles  DVM  MS 《Veterinary radiology & ultrasound》2000,41(1):41-43

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The BamHI site in the Internal Transcribed Spacer Region of Mungbean ribosomal RNA gene is partially methylated     

Ajay Saini  T. Gopala Krishna  K. Sreenivasulu Reddy  Narendra Jawali 《Euphytica》2000,114(1):55-59

The 18s-5.8s-25s ribosomal gene (18s-25s rDNA) in higher plants is present in multiple copies, on different chromosomes, as tandemly repeated units. Among the multiple BamHI sites that occur in the repeat unit, only the site in the middle of the 25s rRNA coding region is methylated in most cereals and pulses. BamHI restriction enzyme analyses of the mungbean 18s-25s rDNA showed the presence of two populations. Nearly 50% of the 18s-25s rDNA population had BamHI site situated in the internal transcribed spacer region (ITS-BamHI) resistant to cleavage by BamHI. The amplified ITS fragment was completely digestible by BamHI showing that partial cleavage by BamHI is not due to variation in the recognition sequence but most probably due to methylation. The complete cleavage of the ITS-BamHI site by BstYI that recognizes BamHI site but is insensitive to methylation confirms that the ITS-BamHI site is methylated. Methylation is probably due to the presence of a guanosine residue adjacent to the 3′ cytosine in the recognition sequence. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Imazaquin Spray Retention,Foliar Washoff and Runoff Losses under Simulated Rainfall     

Krishna N. Reddy  Martin A. Locke 《Pest management science》1996,48(2):179-187

Spray retention and foliar washoff of imazaquin in smooth pigweed (Amaranthus hybridus L.) and sicklepod (Senna obtusifolia (L.) Irwin and Barneby) were investigated. Imazaquin (70 g AI ha⁻¹) was applied alone, with nonionic surfactant ‘X-77’ or organosilicone-based nonionic surfactant ‘Kinetic’ to plants at two- to five-leaf stage and subjected to 2·5 cm rainfall in 20 min either 1 or 24 h after application. Imazaquin spray retention was higher with adjuvants than without. Retention was similar between adjuvants in smooth pigweed but ‘Kinetic’ retained twice as much imazaquin as ‘X-77’ in sicklepod. Rainfall 1 h after application washed off three-quarters of foliar residues regardless of plant species or adjuvant. However, at 24 h after application, foliar washoff was lowest with ‘Kinetic’ followed by ‘X-77’ in both species. Imazaquin washoff ranged from 33 to 88% in the two species at 24 h after application. Overall, imazaquin activity was similar with either adjuvant in smooth pigweed but ‘Kinetic’ was more effective than ‘X-77’ in sicklepod. Runoff losses from the surface of a Bosket sandy loam (Mollic Hapludalfs) soil in runoff trays (1·2% slope) were also studied. Imazaquin was applied as above to trays with and without smooth pigweed canopy. A 2·5-cm rainfall was applied in 20 min at 24 h after application. Runoff samples collected in one-litre fractions were analyzed by enzyme-linked immunosorbent assay. Sediment (but not water) in runoff was greatly reduced (56%) by pigweed cover as compared to bare trays. Imazaquin in the first litre of runoff was higher than in subsequent runoff fractions regardless of pigweed cover. Total imazaquin lost in runoff was higher in pigweed cover (23%) than bare trays (16% of applied). Imazaquin concentration in 10–20 cm soil depth in pigweed cover trays was higher than in bare trays. These results suggest that imazaquin is vulnerable to foliar washoff and the herbicide washed off could move in the aqueous phase due to shorter contact time with soil for sorption.  相似文献   

An approach to land-use planning in a hilly watershed using geographical information system     

J. Adinarayana  N. Rama Krishna 《Land Degradation \u0026amp; Development》1995,6(3):171-178

The eco-socio-economic balance of a region can be preserved by proper land-use planning, particularly in hilly watersheds where erosion caused by rainfall is an ever-present threat. This paper describes a methodology developed to compile a treatment-oriented land-use planning scheme for a hilly watershed using a geographical information system (GIS). A remote sensing based physiographic soils map and a digital elevation model (DEM) are the sources of soil depth and slope steepness classes, respectively, and are the information databases for GIS analysis. The GIS was used to integrate these databases and provide tools for manipulation of the data. A set of knowledge-based rules was formed from the classification scheme formulated by Sheng and Stennett (1975) for hilly watersheds, modified to allow for the local land-use patterns. These rules were used to manipulate the databases and allow the establishment of a sustained land-use system in the watershed with proper soil and water conservation measures. This biological engineering scheme would be a safeguard against soil erosion and other environmental threats. A priority sub-watersheds delineation survey conducted in the watershed indicates significant variation in the silt yield index values, which calls for conservation planning in earnest in cases of high and very high priority sub-watersheds.  相似文献